21431405856 has 192 divisors, whose sum is σ = 66032983296. Its totient is φ = 5958451200.

The previous prime is 21431405839. The next prime is 21431405881. The reversal of 21431405856 is 65850413412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14353846 + ... + 14355338.

It is an arithmetic number, because the mean of its divisors is an integer number (343921788).

Almost surely, 2^21431405856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21431405856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33016491648).

21431405856 is an abundant number, since it is smaller than the sum of its proper divisors (44601577440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21431405856 is a wasteful number, since it uses less digits than its factorization.

21431405856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2075 (or 2067 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 39.

The spelling of 21431405856 in words is "twenty-one billion, four hundred thirty-one million, four hundred five thousand, eight hundred fifty-six".